Firing mechanism for firearms



. R Mm 0\ Mm Q a 4 E \v I E I Samuel [3. Green Oct. 27, 1953 s. G. GREEN FIRING MECHANISM FOR FIREARMS Filed Oct. 25, 1950 Patented Oct. 27, 1953 2&56 636 UNITED STATES PATENT OFFICE FIRING MECHANISM FOR FIREARMS Samuel G. Green, Gray, Ga.

Application October 25, 1950, Serial No. 192,100

1 Claim. (01. 42-69) (Granted under Title 35, U. S. Code (1952). see. 266) The invention described in the specification and claims may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to automatic guns and more specifically to improvements in firing pin mechanisms for machine guns having a high firing rate.

An object of the invention is a firing pin mechanism for the elimination of primer base blowing.

Another object of the invention is the reduction of mass of the firing pin assembly which travels rearwardly at high velocity recoil to contact the sear.

Another object of the invention is the elimination of alignment requirements which in the conventional firing pin requires three bearings to give the pin necessary physical support.

Another object of the invention is a firing pin having its primer contacting member made of alloy steel to withstand the erosion efiect of the corrosive gases and the rear section made of carbon steel since it is not subjected to elevated temperatures or the erosive or corrosive effect of powder gases.

Another object of the invention is the combination of a recoil plate and front section firing pin assembly arranged so that the best conditions of guiding, sealing and functioning can be assured.

Another object of the invention is the elimination of the excessive recoil of the firing pin and firing pin extension experienced when the one piece firing pin is employed.

Another object of the invention is placing the rearward movement of the firing pin assembly under the mechanical control of the cocking lever, so as to assure correct timing of the firing mechanism. The specific nature of the invention as well as other objects and advantages thereof will clearly appear from the following description and accompanying drawings in which:

Figure 1 is a vertical sectional view taken along the longitudinal axis of the bolt, showing the firing pin mechanism in position just prior to the bolt going into recoil;

Figure 2 is a sectional view taken along the longitudinal axis of the bolt showing the floating striker and firing pin of the invention;

Figure 3 is an end view of the striker and firing pin shown in Figure 2;

Figure 4 is a fragmentary vertical sectional view taken along the longitudinal axis of the bolt showing a modification of the arrangement in Figure 1.

The current type of firing pin, which is a. one piece pin, for an automatic gun operating at a rate of approximately 1200 rounds per minute is subjected to severe impact due to the high spring load required to drive the firing pin in order to fire the cartridge in the short interval after the gun is nearing the in-battery position. In addition to the foregoing, the use of high pressures in ammunition to obtain higher required projectile velocities has resulted in a greater setback load on the primer base of the cartridge and firing pin so as to induce pierced and blown primers. The blowing of the primer imparts an abnormal force tothe one piece firing pin causing it to be driven violently and hammer the firing pin extension against the sear member. The improved firing pin mechanism of this invention is provided with a floating striker member supporting a firing pin which has a setback but slightly greater than the protrusion of the firing pin beyond the face of the recoil plate. A plunger extension member is provided with a relatively light spring for actuating a plunger member intermediate the striker and extension. Due to the limited setback of the firing pin the primer base is supported during the firing period which prevents the primer base from setting back so as to be pierced.

In Figure 1 thereis shown a preferred embodiment of the invention wherein reference numeral l indicates a bolt having bore 2 therein housing a firing pin mechanism comprising striker 3, plunger 4, plunger bearing 5 threadably secured within bore 2, plunger extension member 6 and plunger driving spring 1. Reference numeral 8 indicates the usual cock-ing iever, which has one end 9 for engagement with the top-plate bracket Ill and its opposite end II for engagement with the plunger extension member 6, and I2 indicates the sear. Fixed, in'the front end'of bore 2 is a recoil plate [3 provided with a bore I311 having a reduced portion I31) forming a'shoulder [39 intermediate the ends'of the bore I311. The firing pin M is slidably received in reduced portion 53b for engagement with primer base 20. For a short distance behind the recoil plate the bore 2 is reduced as indicated by reference numeral I5 providing bearing surface for the slotted body It of the striker member 3. The slots being indicated at H. The rearward motion of the striker 3 is arrested by the plunger bearing 5 which has its forward end spaced a predetermined distance from the reduced portion I5 of the bore 2. The head H3 in icounterrecoil movement contacts the cup I 9a to limit the counterrecoil movement of the body tioned between the head l8 andreducedrp'ortion- 10.

I5 resiliently spaces the firing pin M from the primer base 20 of the cartridge 2|. 'lfhezplungen 4 is provided with a flange 22 which abuts one end of the plunger bearing Wandlimits-thefor ward travel of the plunger. flange 22, the plunger 4 is afiixed to one end of the plunger extension 6 as by means== of-pin-zih The sear stop assembly 24 has a. pin 25 extending through the slot 26- in the plunge extensionu6. 'Iiheespring his:-positionediin-theslotlfi betweenrpini2-3 andpin 25? of the-searrstopzassembly.

Figure illustrates; a modified! form: of? the invention: whereini thereis: a: bolt 31): having.- a borev 3;I- reduced? as} at: 3.1a: to accommodate a p1l1ng81"32: which has? its; iorward end extended into*a*1bore:33:of theerecoil plate 3.4-? Irrthebore 334 of; therecoiLplate-there is; positioned; a: striker member: 35. having; aflixedr to: its? forward end: a firing pinr136-and-a flange-3! at its-opposite. end fort engagement-withthemplunger 32.; A spring 3fle-resiliently spaces-thestrikermember from: the cartridge. The: firing; pin:- is longitudinally: sup:- ported: byvthe walls: ot. the: reduced; section 3311 of.,the.-bo re- 33;

Inoperation; the-sear releaseswhe; plunger? ex"- tension. and the spring; therein; drives; the extermision and-plunger which driveithevstrikermember to. cause-thefiringr pinrto; indent? the base of the primer andv fire; theprimer-,, the base; of which is.supported=not;only by the recoilplate, but ;-in part-by the, firing pin-which; when-in; recoil posi:- tion isrsubstantially flush with the,-- exposed sunf ace. of; the recoiLplateev In.the,usualitype of firing-pin, the pim in recoil travelsthe entire distance requiredfor engagement of the extension withstheisear and; leaves thecenter-ofithe basevoi the-primer unsupported to. be blowninto the :boreimwh-ich rtherpinrtra-vels and resultsinexcessiver recoil oi-thepin. This excessive. recoil; causes: a heavy impact load; on thesear and thefiring. pin extension which refbounds. and obtains: false: engagement withthe sear. The, extension; releases before the firing point of the, bolt. is. reached tozcauseea riding down of the 1. conventional, firing pin: and; exten-.- sion on the, cooking, lever: which is: purposely blocking the-firing pin. assembly before the re* lease position is reached. and results in: alight blow andfailure.tofire.the,cartridge;. The firing pi'n mechanism, of this inyentiom eliminates the foregoing since the firing pin and.- striken are Adjacent to the:

arrested in the recoil travel, leaving the plunger and extension under the mechanical control of the cooking lever to assure correct timing of the firing mechanism.

I claim:

In; an automatic firearm; ai bolt-reciprocable therein between recoil and battery positions, there being an elongated horizontal stepped bore formed in said bolt and comprising a short forwardrenlarged portion, an elongated medial portion ofreduced' diameter, and a rear enlarged portion; afiring pin and plunger mechanism reciprocable, insaid horizontal bore and comprising, a' floating striker slidable in said forwarm enlarged bore portion, said striker including a main body portion providing a sliding fit with-thewall of said forward enlarged portion, and. a forward reducedrportion forming a firing in, means in said forward enlarged bore limiting" the forward movement of saidf striker in counter r'ec'oil to provide a=- predetermined: prout'rus'ion of" saidfir'ing-r pin beyond the forward wall ofsaidbolti wnen'saiu gun is ffred; resilient means cooperating'with said forward movement limiting means tonormally urge said striker intoretracted position with the forward endi of said firing pin flush with the forward wall: of saidbolt; said striker beiii-glimited? in: rearward movement to an extent slightly in excessei? said predetermined protrusiorr by the -should'er-formed by said forward enlarge'd bore portion and said medial redilcedbore portioman elongated tiibu lar plunger reciprocable in said medial: reduced portion for positive errgagenrien't said striker, a flanged-' enlargement o'r'ithe rear end of said plunger; said enlargement -slidably engaging said enlarged reanboreportion, saider'il'argerm'ant also adapted to abut the shoulder between said enlar ed rear" bore ortion and' said medial bore portion when said gunis fired to" limit tl'ie forward travel o'fsaid' plunger, a" hollow sleeve' in said enlarged rear bore portion: integralwith said: enlargement; ahelical: spring in: said" hunb'w sleeve having its forward end engaging said errlarger nentand itsr'ear:end'atuttinga sto'p' me'mher-integral with: said bolt, said helical spring being compressedby: the" rearward movement of said bolt; whereby on release of said" bolt said spring drives said plunger forward to propel sa'i'd fi'ri'ng pin intocontact the. primer ofa proponent cartridge.

SAMUELXG; GREEN;

References Cited? inrthet fileeof this patentr UNITED STATES PATENTS Number Name Date V I 7. 1,488,439 Rimailho Mar. 25., 1924 2, l25,434,, Loomis Aug. 12;..1947 2494;603; Wyk0ff. Jan. I? 1950 2503309 WeiSSv A1311.v L1,, 1950 

